feat(core): add stale permission entries sub-section to K3PT ST4T3

Adds a "stale permission entries" sub-section within the K3PT ST4T3 pane
on /core.html showing agents with explicit capability/tool-group JSON
entries but no live container — typically renamed or manually-deleted agents
whose entries persisted (e.g. the old "root" manager name after rename to
"ruth").

Each ghost agent gets a "✕ clear perms" button that calls
DELETE /api/permissions/{agent} (added in the prior commit). Lazy-loaded
on first K3PT ST4T3 tab activation; auto-refreshes on capabilities_changed
and tool_groups_changed SSE events.

core.js: track liveContainerNames from /api/state.containers; add
renderStalePerms + fetchAndRenderStalePerms; hook tab onShow + SSE handlers.

system-sections.css: new .tombstones-stale-* selectors for the ghost list
rows and error message.

core.html: add #tombstones-stale-perms div inside the K3PT ST4T3 pane;
expand comment to describe both sub-sections.

frontend/packages/dashboard/src/core.js

@@ -20,12 +20,15 @@ let metaInputsState = [];
 let metaUpdateRunning = false;
 let tombstonesState = [];
 let rebuildQueueState = [];
+// Live container names — used by the stale-perms ghost filter.
+let liveContainerNames = new Set();
 
 function syncFromSnapshot(s) {
   metaInputsState = (s.meta_inputs || []).slice();
   metaUpdateRunning = !!s.meta_update_running;
   tombstonesState = (s.tombstones || []).slice();
   rebuildQueueState = (s.rebuild_queue || []).slice();
+  liveContainerNames = new Set((s.containers || []).map((c) => c.name));
 }
 
 // ─── meta inputs ──────────────────────────────────────────────────────────
@@ -447,6 +450,79 @@ function renderTombstones(s) {
   root.append(ul);
 }
 
+// ─── stale permission entries (K3PT ST4T3 pane sub-section) ──────────────
+// Agents with explicit capability / tool-group JSON entries but no live
+// container (e.g. renamed agents like the old "root" manager name). Lazy-
+// loaded on first "kept" tab activation; refreshed when perm data changes.
+let stalePermsLoaded = false;
+
+function renderStalePerms(root, ghosts) {
+  root.replaceChildren();
+  if (!ghosts.length) return;
+  root.append(el('p', { class: 'tombstones-stale-heading' }, 'stale permission entries'));
+  root.append(el('p', { class: 'meta' },
+    'agents with explicit capability or tool-group entries but no live container '
+    + '(typically renamed or manually-deleted agents whose JSON entries persisted).'));
+  const errP = el('p', { class: 'tombstones-stale-err', hidden: true });
+  const ul = el('ul', { class: 'tombstones-stale-list' });
+  for (const name of ghosts) {
+    const li = el('li', { class: 'tombstones-stale-row' });
+    li.append(el('span', { class: 'tombstones-stale-name' }, name));
+    li.append(el('span', { class: 'badge badge-muted' }, 'stale perms'));
+    const btn = el('button', {
+      type: 'button',
+      class: 'btn btn-destroy',
+      title: 'remove explicit capability and tool-group entries for ' + name,
+    }, '✕ clear perms');
+    btn.addEventListener('click', async () => {
+      btn.disabled = true;
+      errP.hidden = true;
+      try {
+        const resp = await fetch('/api/permissions/' + encodeURIComponent(name), { method: 'DELETE' });
+        if (!resp.ok) {
+          const msg = await resp.text().catch(() => String(resp.status));
+          errP.textContent = 'failed to clear perms for ' + name + ': ' + msg;
+          errP.hidden = false;
+          btn.disabled = false;
+          return;
+        }
+      } catch (err) {
+        errP.textContent = 'failed to clear perms for ' + name + ': ' + err;
+        errP.hidden = false;
+        btn.disabled = false;
+        return;
+      }
+      await fetchAndRenderStalePerms();
+    });
+    li.append(btn);
+    ul.append(li);
+  }
+  root.append(ul, errP);
+}
+
+async function fetchAndRenderStalePerms() {
+  const root = $('tombstones-stale-perms');
+  if (!root) return;
+  try {
+    const [capsResp, tgResp] = await Promise.all([
+      fetch('/api/capabilities'),
+      fetch('/api/tool-groups'),
+    ]);
+    const capsData = capsResp.ok ? await capsResp.json() : { assignments: {} };
+    const tgData = tgResp.ok ? await tgResp.json() : { assignments: {} };
+    const explicit = new Set([
+      ...Object.keys(capsData.assignments || {}),
+      ...Object.keys(tgData.assignments || {}),
+    ]);
+    const ghosts = [...explicit].filter((n) => !liveContainerNames.has(n)).sort();
+    renderStalePerms(root, ghosts);
+  } catch (err) {
+    root.replaceChildren();
+    root.append(el('p', { class: 'meta' }, 'failed to load perm data: ' + err));
+  }
+  stalePermsLoaded = true;
+}
+
 // ─── container load (live cgroup poll while the LOAD sub-tab is open) ──────
 let containerLoadTimer = null;
 
@@ -602,6 +678,14 @@ const SSE_HANDLERS = {
     tombstonesState = (ev.tombstones || []).slice();
     renderTombstones({ tombstones: tombstonesState });
   },
+  // Refresh the stale-perms sub-section when perm data changes (a ghost
+  // was cleared, or perms were saved for an agent whose name collides).
+  capabilities_changed(_ev) {
+    if (stalePermsLoaded) fetchAndRenderStalePerms();
+  },
+  tool_groups_changed(_ev) {
+    if (stalePermsLoaded) fetchAndRenderStalePerms();
+  },
 };
 
 // ─── boot ─────────────────────────────────────────────────────────────────
@@ -635,6 +719,9 @@ async function init() {
     onShow: (id) => {
       if (id === 'load') startContainerLoadPolling();
       else stopContainerLoadPolling();
+      // Lazy-load stale-perms on first K3PT ST4T3 activation; always
+      // re-fetch on subsequent visits in case perms changed.
+      if (id === 'kept') fetchAndRenderStalePerms();
     },
   });